There's no easy explanation for it, yet this month, the city's two biggest theaters have made local history. Never before have the Old Globe and La Jolla Playhouse simultaneously staged world-premiere, Broadway-class musicals, both artistically deserving hits and both enthusiasticallyreceived.

The Globe's "Dirty Rotten Scoundrels," based on the Frank Oz film with a new score by David Yazbek, and starring John Lithgow as a debonair con man, has some standing-room tickets left for performances that close here Nov. 7.

"Jersey Boys," the Des McAnuff-directed musical about Frankie Valli and the Four Seasons, featuring Seasons hits, pop standards, an ace cast and nostalgia to burn, still has some seats for a just-announced extension through Dec. 5, and "preferred standing room" for some shows throughout the run.

These ambitious new shows cap a five-month period when 30 musicals have been seen or produced in San Diego County, a record here by anybody's calculus.

San Diego theatergoers have had reason to feel lucky before. "The Who's 'Tommy' " got its start at La Jolla Playhouse in 1992. So did "Into the Woods" and "The Full Monty" (both at the Old Globe) and "Thoroughly Modern Millie" (at the Playhouse).

Those managements have launched Broadway-bound revivals of "Damn Yankees" (Globe) and "How to Succeed in Business Without Really Trying" (Playhouse). They've served up caviar like Randy Newman's acerbic "Faust" (Playhouse) and Adam Guettel's haunting "Floyd Collins" (Globe).

But don't look for deeper meaning in the current serendipitous aligning of the musical theater stars.

"I would call this a coincidence – neither synergy nor an impulse toward competition," said Lou Spisto, executive director of the Old Globe.

"When you have theaters in the business of periodically doing these large productions that transfer (to Broadway), perhaps one or two out of six will be big hits. So here we are with two terrific shows, both very well received – and in the Globe's case, a completely new show – new book, new music and lyrics."

Noting that such ambitious ventures are "horrifically risky for both the commercial producers and the nonprofit theaters alike," Spisto concluded that "the big beneficiary is San Diego."

Since the mid-1980s, when McAnuff earned his first Tony Award for directing with the Roger Miller-scored "Big River," the Globe and the Playhouse, both not-for-profit theaters operating for the public good, have pioneered alliances with commercial producers. These private-public partnerships have developed new musicals (and sometimes plays) that tour or transfer to New York.

True to form, the Globe show, with cast and collaborators intact, opens March 3 at Broadway's Imperial Theatre. There it will cost $11 million, according to lead producer Marty Bell, part of a team that includes a new entrant in the movie-to-musical game, MGM Onstage. The Globe "Scoundrels" cost about $4.2 million, according to Spisto, who said the local theater's share was $1 million, with the commercial producers kicking in $3.2 million.

With its shimmering seaside designs by famed architect David Rockwell and its double elliptical turntable floors, "Dirty Rotten Scoundrels" is by far the most technically complex and expensive production in Globe history. Yet most of it was painstakingly built and painted here, in the Globe scene and costume shops.

Broadway audiences will see essentially the same show, with four or five more set pieces added in the bigger New York house, and a larger band than the Globe pit could accommodate. "The piece was written very cinematically, making it lush and beautiful and technically complicated," said Spisto, distinguishing its remarkable fluency from that of a more traditional "stop-and-start" structure for a book musical.

Terrence Dwyer, La Jolla'smanaging director, said the Playhouse contributed just short of $1 million to the equally fluent if less elaborate production of "Jersey Boys," with the other $850,000 coming from a team of producers headed by Dodger Productions, a New York group that includes Playhouse artistic director McAnuff.

"Jersey Boys" has no Broadway date – yet. McAnuff is in New York working with actor-comic Billy Crystal toward a Dec. 5 opening of "700 Sundays," the autobiographical show Crystal developed here as part of the Playhouse's Page-to-Stage program.

McAnuff already has another Playhouse-launched musical on Broadway, the poorly received, yet still running "Dracula, The Musical." La Jolla Playhouse will open a new facility on the UCSD campus next month, and McAnuff will direct a French comedy to open its third theater in 2005, so it's unlikely that "Jersey Boys" will see the lights of the Great White Way anytime soon.

Southern California reviews of the show have been largely enthusiastic. But, like the Abba-scored "Mamma Mia!" and Billy Joel-fueled "Movin' Out," "Jersey Boys" capitalizes on a precomposed score, so it may not win the hearts and pens of leading New York critics.

If "Jersey Boys" does transfer and prove a hit, the Playhouse stands to recoup some of its investment in the show, as it has with other musicals it launched, including "Tommy." Similarly at the Globe, said Spisto, "If the show is very successful after a year or so, especially if there's a tour, the Globe can make some of its investment back."

So come Tony Awards season next spring, it's unlikely that "Dirty Rotten Scoundrels" will be competing head-to-head with "Jersey Boys."

In the meantime, San Diego audiences can feel spoiled and bask in the buzz.